The present invention provides methods, reagents, and kits for diagnosing and treating cancer in a mammal, e.g., a human. This invention is based upon the discovery that Pellino 1 or 2 is overexpressed and/or amplified in cancer. Methods to detect cancer or a propensity to develop cancer, to monitor the efficacy of a cancer treatment, and to treat cancer, by inhibiting the expression and/or activity of Pellino 1 or 2 in a cancer cell are included.